202 UTILIZATION OF MINUTE LIFE. 



twenty- six Nats. He cut the head off the same 

 Nais twelve successive times, and twelve successive 

 times the head was reproduced. M. Flourens, in 

 his work " Sur la Longevite Humaine," etc., says,, 

 " There exists in the animal economy not only a 

 force of development which brings each part up to 

 the precise term assigned for it, but an individual 

 force of reproduction, first brought to light by 

 Tremblers experiments on polyps." 



Look again at the marvellous manner in which 

 the marine worms, Sabularia and T&rebella, construct 

 the tubes they inhabit, by means of the grains of 

 sand and rock of the sea- shore, or at the curious 

 phosphorescent faculty, or emission of light in the 

 dark, possessed by many marine worms, and even 

 by our common earth-worm (Lumbricus) , at certain 

 seasons of the year* ; or still again, at the curious 

 moveable organ of deglutition observed in certain 

 voracious fresh- water Planarice, which even after it 

 has been torn away from the animal's body, con- 

 tinues to swallow down everything that is presented 

 to its gluttonous orifice ! 



These worms may not appear to be directly 

 useful to man, or to his commerce, save, perhaps, as 

 articles sold for the aquwriwrii, which has lately be- 

 come so fashionable. But, on the other hand, what 



* See my "Phosphorescence, or the Emis8ion of Light by 

 Minerals, Plants, and Animajs." London, 1862. 



